code: def test_new_column_names(process_test_df):
      """
      Test that a new column name is created when
      `new_column_name` is not None.
      """
      result = process_test_df.process_text(
          column_name="text",
          new_column_names="new_text",
          string_function="slice",
          start=2,
      )
      expected = process_test_df.assign(
          new_text=process_test_df["text"].str.slice(start=2)
      )
      assert_frame_equal(result, expected)
  
imports: import numpy
  import pandas
  import pytest
  from pandas.testing import assert_frame_equal
label_desc: Use image node_id 11 for calling a global function with example usage: test_new_column_names(process_test_df) without return types